The star witness in Silvio Berlusconi’s trial for paying for sex with an underage prostitute is to testify next month, lawyers said on Monday, as legal woes threaten his faltering re-election campaign.

Moroccan-born pole-dancer Karima El-Mahroug — better known by her professional nickname of “Ruby the Heart Stealer” — is a witness for Berlusconi’s defence and is expected to say she never had sex with him.

Prosecutors say Berlusconi had sex for money with “Ruby” when she was 17.

While the age of consent in Italy is 14 and prostitution is decriminalised, paying for sex with someone under 18 is a criminal offence.

El-Mahroug has failed to testify on two previous occasions because she said she was in Mexico — a strategy, prosecutors said, by the defence to try and draw out the trial until after elections expected on February 17.

Prosecutor Ilda Boccassini said it was a “delaying tactic” saying she found El-Mahroug’s “sudden decision” to go to Mexico suspicious.

But her lawyer Paola Boccardi on Monday said El-Mahroug would return from Mexico on January 12 and could therefore testify at a hearing on January 14.

Prosecutors will present their final arguments on January 28 and the defence will speak on February 4 before a verdict presumably later that month.

Berlusconi is also accused in the trial of abuse of power for intervening to have El-Mahroug released from police custody when she was arrested for theft.

Prosecutors say that he was acting to stop her spilling any secrets, while Berlusconi claims he wanted to avoid a diplomatic incident since he believed that she was then Egyptian president Hosni Mubarak’s niece.

Berlusconi, who has denied all charges, potentially faces several years in prison on the charges which date back to when he was still prime minister.

Given sentencing guidelines for people over 70 years of age and the delays in the Italian justice system, he is unlikely to see the inside of a prison even if convicted.

Starting on January 18, Berlusconi will also be appealing a conviction for tax fraud linked to his media business activities which if upheld could lead to a one-year prison sentence and a five-year ban from holding public office.

The two trials are only a fraction of multiple recent or pending legal cases involving Berlusconi and a sleazy network of associates including a drug dealer, a fraudster, three alleged pimps and a senator accused of mafia ties.

Giampaolo Tarantini, a businessman from southern Italy who already has a conviction for dealing in cocaine, is due to go on trial starting on February 8 for procuring prostitutes for soirées hosted by the party-loving Berlusconi.

Tarantini has denied this, saying he only sent female guests and whether they slept with the then prime minister or not was none of his business.

Berlusconi is also being investigated for a 500,000-euro ($658,000) payment to Tarantini, which prosecutors suspect was hush money for the alleged pimp.

Also under investigation for the payment is Valter Lavitola, a former close associate of Berlusconi jailed for fraud in a separate case earlier this year, who is suspected of being the intermediary between Berlusconi and Tarantini.

The investigations into Berlusconi’s parties have also produced a separate trial on pimping charges against three friends of Berlusconi: journalist Emilio Fede, showbiz producer Lele Mora and former showgirl Nicole Minetti.

Mora has an earlier conviction for drug dealing from the 1980s and was sentenced to four years in prison last year for fraudulent bankruptcy.

Minetti, Berlusconi’s former dental hygienist and a member of the Lombardy regional council, is currently under investigation for misuse of public funds.